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Issue: Catchment scale influences - Hydrological condition - Ground-water availability and human use

This is an issue under the Inland waters theme of the Data Reporting System.

Why we need to know about this issue

Groundwater is important in maintaining groundwater dependent ecosystems such as mound springs, perched lakes, some wetlands and floodplain vegetation such as trees that have root systems extending down into the aquifer to take advantage of the water during dry periods. Groundwater dependent ecosystems represent a small, but diverse and important component of Australia's biological diversity. One of the most significant groundwater dependent ecosystem is baseflow to rivers. As such, the management of groundwater is also critical to surface water quality and availability.

Groundwater is also a significant human water resource and in some areas the major water source. The 2001 State of the Environment (SoE) report noted that extraction of groundwater was continuing at an unsustainable rate

The irrigation sector is the greatest user of water. Demand for groundwater is influenced by the quality of the resource, with some groundwater being of higher quality than surface waters and other resources unable to be used without treatment. Most of the groundwater extracted is used for irrigation, and the annual volume extracted for irrigation doubled between 1985 and 1996/97. Groundwater used for irrigation is sometimes mixed with other water supplies to meet quantity or quality requirements.

Irrigation-induced salinity is caused by increased 'leakage' of water from the surface into groundwaters due to over-irrigation or the irrigation of inappropriate soils.

Demand for water supply for urban use is also growing across all sectors. Developing water resources to meet the growing demand presents major challenges because of competition for water and environmental issues. There is also an uncertainty associated with climate change and the potential for decreased yield from existing water supply catchments. As a result, there is considerable potential for conflict over supplying increased urban water demands.

The trend in total urban water use is determined by changes in population, per capita use and uptake of water-efficient technologies.

Indicators

• IW-05 Average annual groundwater depth 
  Depth to a groundwater resource is an important factor in determining the feasibility of developing the resource and is therefore a surrogate indicator for availability of the resource for human use as well as a direct indicator for the pressure of rising or falling groundwater on land and biodiversity. Groundwater levels fluctuate naturally with the seasons and in some aquifers fluctuate due to the high recharge rates, low storativity of the aquifer and extractions. Many of the good quality groundwater aquifers in Australia are highly developed, with some having falling levels due to over-extraction. In other areas with falling levels, drought conditions over the last few years are the cause. Groundwater levels do not respond immediately to recharge, and so the effects of drought or over-extraction may occur years after the stress on the system.
  Salinity and waterlogging problems can occur where watertables have risen to near the ground surface due to vegetation clearing. This can reduce the availability of groundwater for both human and natural uses, as well as increasing surface salt with consequential impacts on land, surface waters and biodiversity.
  In the absence of data on groundwater depth, estimates of sustainable yield are reported as a measure of availability of groundwater for human use. Sustainable yield is the level of extraction measured over a specified planning time frame that should not be exceeded to protect the higher value social, environmental and economic uses associated with the aquifer. Sustainable yield does not provide insight into the pressure of rising groundwater on the land, biodiversity or surface waters.
• IW-06 Average annual groundwater pressure 
  Throughout Australia there are many artesian bores that require capping to prevent the loss of the resource. Uncapped bores can result in a loss of groundwater pressure and reduction in flows over time. Loss of groundwater pressure can affect dependent ecosystems such as biota in mound springs and other users of the aquifer. Reduced pressure can also lead to a reduction in access by humans to the resource.
• IW-08 Groundwater used for irrigation 
  Quantity of groundwater used for irrigation is a direct measure of this pressure.
• IW-09 Groundwater used for urban/industrial 
  Quantity of groundwater used for urban and industrial purposes is a direct measure of this pressure and the effectiveness of management responses to it.
• IW-44 Sustainable yield determination 
  The sustainable yield will help determine availability of water for human and other use.
• HS-46 Usage of water efficient appliances 
  Water supply for human settlements is also extracted mostly from groundwater sources. Increased use of water efficient appliances in households will contribute to reducing the demand for water extracted from these sources.
• HS-42 Water consumption per capita 
  Per capita water consumption is an indicator of the pressure of human demand on groundwater sources.
• HS-41 Water consumption by sector 
  Water used by human settlements are derived from surface water and groundwater sources. Extraction of water for human uses impact on the hydrological condition of natural water bodies.
• HS-44 Urban stormwater and wastewater reuse 
  Water supply for human settlements is often extracted from groundwater sources. Increased use of water efficient appliances in households will contribute to reducing the demand for water extracted from these sources.

Related issues

• Inland Waters - Catchment scale influences- Hydrological condition- Surface-water availability and human use 
• Human Settlements - Pressures created by human settlements on the environment- Water use